The King is on his first foreign trip since his cancer diagnosis and took a day of rest before beginning his tour on Sunday.

Attending a church in a north Sydney suburb, the King signed a bible brought over with the First Fleet.

However, it wasn't the first time the King had done so and his signature was visible, alongside Princess Diana's, from a trip the couple took in 1983.

Other royals, seemingly including Prince Andrew and Sarah Ferguson, and Prince William and the Princess of Wales, had also signed the page.

Also on the first day, the King joked about the "sands of time" as he expressed his joy at being back in Australia talking to politicians.

The monarch presented an hourglass - a "speech timer", he called it - to the parliament of New South Wales to mark the 200th anniversary of its upper house.

"With the sands of time encouraging brevity," the King quipped, "it just remains for me to say what a great joy it is to come to Australia for the first time as sovereign, and to renew a love of this country and its people which I have cherished for so long."

It seems he could not resist setting the hourglass's fine sand in motion as he gifted the time piece to the parliament.

"Democratic systems must evolve, of course, to remain fit for purpose, but they are, nevertheless, essentially sound systems, as I said in this building 50 years ago," he said.

"When underpinned by wisdom and good faith, democracy has, I believe, an extraordinary capacity for innovation, compromise and adaptability, as well as stability."

Before the service at St Thomas' Anglican Church, its Rector Michael Mantle made those gathered laugh when he told them: "Jesus said you will not know the day nor the hour when the King will come."

When the couple first arrived they met some children at the church door as a group of protesters could be heard shouting "not my king" but were drowned out by shouts of "hip hip hooray".

The Rector's wife Ellie Mantle brought a rugby ball, cricket ball and stuffed koala, gifts for the royal grandchildren Prince George, Princess Charlotte and Prince Louis.

"It's a great honour for us as it's the first opportunity for the public to see the King and Queen," she said.

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Afterwards, the King and Queen spent time shaking hands with well-wishers outside and the monarch even spotted an old friend among the faces - his former polo teacher Sinclair Hill, described as Australia's greatest player of the sport.

He was joined by his wife Wendy Hill who was kissed on both cheeks by Charles and said afterwards: "He is a lovely man and the fact that he has not been well and still came... The effort he puts in to talk to all these people. I thought he looked terrific."

Around 100m away a small group of people, all supporters of First Nations resistance to colonisation, held up a large banner with the word "decolonise".

Wayne Wharton said: "We are asking King Charles respectfully to begin the process of decolonisation, to join with the Australian government and negotiate with the Aboriginal people for reparations for the illegal settlement and colonisation of so-called Australia."